Silylated polyurethane compositions and adhesives therefrom

ABSTRACT

A silylated polyurethane composition containing polyester based polyurethane prepolymer. The silylated polyurethane composition when partially silylated is especially useful for pressure sensitive adhesives where it imparts superior adhesive and cohesive performance thereto.

BACKGROUND OF THE INVENTION

This invention relates to silylated polymers and to pressure sensitiveadhesive (PSA) compositions containing same.

There are certain adhesive applications for which solvent resistance ishighly desirable. These include automotive, aerospace, industrial andconsumer labels where exposure to aromatic, aliphatic solvents and oilsoccurs. Solvent-resistant adhesives are also required for labels used byanalytical laboratories such as environmental and medical laboratoriesto prevent loss of critical sample identification information. Furtherapplications include electronic labels or masked areas undergoingfurther processes; dry cleaning labels for garments; degreasingoperations where identification labels or masked-off areas are required,and the like. Adhesive properties of many pressure sensitive orheat-activated adhesives are well suited for use with labels on varioussubstrates. However, these are not significantly solvent-resistant andtherefore it is highly desirable that a solvent-resistant adhesive beprovided.

Solvent-resistant adhesive compositions are known in the art.

JP 56082863 describes a thermoplastic polystyrene-polybutadiene blockcopolymer or a mixture thereof with another thermoplastic rubber ofethylene-vinyl acetate copolymer combined with an acryl-modifiedpolybutadiene.

JP 57207663 describes a compound comprised of ethylenic ionomer resin, apolyurethane resin, a polyethylene resin, a polyamide resin, a polyesterresin, an agent for the thermal curing of a synthetic resin, and athickener.

JP 59172575 describes a solvent-resistant hot melt adhesive comprised ofa polyester amide containing terminal alkoxyl groups prepared byreacting an aminoalkylalkoxysilane compound with a polyester-amidecontaining terminal isocyanate groups.

JP 59174672 describes a solvent-resistant acrylic adhesive comprised ofthe reaction product a vinyl compound (e.g., methyl acrylate, isobutylmethacrylate, etc.) and a vinyl dioxazolone compound.

JP 61047774 describes a solvent-resistant adhesive comprised of aminogroup terminated polyamide resin reacted with a isocyanategroup-containing alkoxysilane that is the addition product of, forexample, hexamethylene diisocyanate and 3-aminopropyltriethoxy-silane.

JP 61218631 describes a solvent-resistant adhesive comprised of asilane-modified polyester resin obtained by reacting a polyester resincontaining a hydroxyl group with an isocyanate group-containinghydrolyzable organosilicon compound.

JP 61218672 describes a solvent-resistant acrylic adhesive comprised ofan unsaturated polyester resin having terminal ethylenic groups which isthe reaction product of a ethylenic compound having isocyanate groupswith terminal hydroxyl groups or carboxyl groups of an unsaturatedpolyester resin.

JP 61218673 describes a solvent-resistant acrylic adhesive comprised ofan unsaturated polyester resin having terminal ethylenic double bondsobtained by reacting epoxy(meth)acrylate with the terminal carboxylgroups of an unsaturated polyester resin having ethylenic double bond inthe molecule.

JP 62057480 describes a solvent-resistant adhesive comprised of apolyamide resin having terminal ethylenic double bonds obtained byreacting a compound having aziridinyl and ethylenic groups with terminalcarboxyl groups of a polyamide resin.

JP 62057479 describes a solvent-resistant adhesive comprised of anunsaturated polyester resin having both terminal and in-chain ethylenicdouble bonds obtained by reacting a compound having aziridinyl andethylenic groups with terminal carboxyl groups of an unsaturatedpolyester resin.

JP 62057478 describes a solvent-resistant adhesive comprised of anunsaturated polyester resin having terminal and in-chain ethylenicdouble bonds obtained by reacting a terminal hydroxyl group of anunsaturated polyester resin with an epoxy (meth)acrylate.

JP 62089782 describes a solvent-resistant adhesive obtained by reactionbetween a high-molecular weight diol, preferably a polyester diol ofpolyethylene-butylene-adipate, a divalent isocyanate compound, a chainextender and a hindered nitrogen atom compound such as one containing apiperizine ring.

JP 03259981 describes a solvent-resistant adhesive comprised of acomposition prepared by compounding a block copolymer and an isocyanateprepolymer. The block copolymer comprises a block consisting of at leasttwo kinds of aromatic vinyl monomer and a block consisting of at leastone kind of a conjugated diene monomer in which at least 50% ofcarbon-carbon double bonds in the block have been hydrogenated (e.g. ahydrogenated styrene-isoprene-styrene triblock copolymer). Theisocyanate prepolymer is obtained by reacting an isocyanate compoundwith a liquid polymer which comprises a polymer of isoprene orisoprene-butadiene mixture and has 1.5-5.0 hydroxyl groups in themolecule and in which at least 50% of the carbon-carbon double bondshave been hydrogenated.

JP 09165565 describes a solvent-resistant adhesive composition which isa blend of a base polymer with a tackifier resin and, optionally, asoftening agent or a wax, a block copolymer which comprises one or morehydrogenated butadiene polymer blocks, one or more of aromatic vinylcompound polymer blocks and one or more polymer blocks substantiallyhaving an olefin polymer structure.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a silylatedpolyurethane composition comprising silylated polyurethane prepolymerobtained from the silylation of a polyurethane prepolymer derived fromthe reaction of polyester polyol possessing an average of at least about2.05 hydroxyl groups and polyisocyanate.

In accordance with another aspect of the invention herein, there isprovided a moisture-curable pressure sensitive adhesive compositionpossessing improved adhesive and cohesive properties comprisingpolyester-based silylated polymer and, optionally, one or more adhesivecompositions.

Further in accordance with the present invention, blends ofsilane-terminated polybutadiene polyurethane or silicone or organic(e.g., natural rubber, SBR, SIS, acrylic, isoprene, polyurethanes)adhesives with silane-terminated polyester polyurethane adhesive areprovided as a means of modifying the peel adhesion and other properties,as more fully described herein below.

DETAILED DESCRIPTION OF THE INVENTION

The silylated polymer of this invention is derived fromhydroxyl-terminated polyester polyol that is reacted with polyisocyanateto provide hydroxyl-terminated and/or isocyanate-terminated polyurethaneprepolymer. Silylation of the hydroxyl-terminated and/orisocyanate-terminated polyurethane prepolymer can be accomplished byreacting the prepolymer with a silane possessing at least onehydrolyzable group and at least one functionality which is reactive forisocyanate, i.e., an active hydrogen-containing group such as hydroxyl,carboxylic acid, mercapto, primary amino or secondary amino.

Polyester Polyol

The hydroxyl-terminated polyester polyol of the present invention arepolyesters having at least two hydroxyl groups (usually 2 to 4 hydroxylgroups) and having each end of polyester molecules thereof terminatedwith hydroxyl groups. When the polyester polyol has 2 hydroxyl groups,both at the ends, it may be thought of as a hydroxyl-terminatedpolyester diol.

Hydroxyl-terminated polyester polyols of the above-described type,averaging more than one predominantly primary hydroxyl group, e.g.,averaging from about 2.0 or more primary hydroxyl groups, are suitablyemployed herein. The hydroxyl-terminated polyester polyols will possessan average of at least about 2.0, and advantageously from about 2.1 upto about 4.5, hydroxyl groups, the hydroxyl groups being predominantlyin terminal positions. In one embodiment of the present invention,blends of hydroxyl-terminated polyester polyols possessing variousaverages of hydroxyl group of the blend which range from about 2.05 toabout 2.75 are provided.

The polyester polyols of the present invention can be obtained byreacting a polybasic acid component and a polyhydric alcohol component.

As the polybasic acid component, there may be mentioned terephthalicacid, isophthalic acid, phthalic acid, malonic acid, dimethylmalonicacid, succinic acid, glutaric acid, adipic acid, trimethyladipic acid,pimelic acid, 2,2-dimethylglutaric acid, azelaic acid, sebacic acid,fumaric acid, maleic acid, itaconic acid, 1,3-cyclopentanedicarboxylicacid, 1,2-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylicacid, 2,5-norbornanedicarboxylic acid, 1,4-naphthalic acid, diphenicacid, 4,4′-oxydibenzoic acid, diglycolic acid, thiodipropionic acid,2,5-naphthalenedicarboxylic acid and the like. These polybasic acids maybe in the form of acid anhydrides, esters, chlorides, etc.

Polybasic carboxylic acids having three or more carboxyl groups, such astrimellitic acid, trimellitic anhydride, pyromellitic acid, pyromelliticanhydride, 4-methylcyclohexene-1,2,3-tricarboxylic anhydride, trimesicacid,5-(2,5-dioxotetrahydrofurfuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylicanhydride, may be used in small amounts in combination with theaforementioned dicarboxylic acids.

As the polyhydric alcohol component, there may be mentioned ethyleneglycol, diethylene glycol, propylene glycol, 1,3-propanediol,1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol,2,4-dimethyl-2-ethylhexane-1,3-diol, 2,2-dimethyl-1,3-propanediol(neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol,2-ethyl-2-isobutyl-1,3-propanediol, 3-methyl-1,5-pentanediol,2,2,4-trimethyl-1,6-hexanediol, 1,2-cyclohexanedimethanol,1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol,2,2,4,4-tetramethyl-1,3-cyclobutanediol, 4,4′-thiodiphenol,4,4′-methylenediphenol, 4,4′-(2-norbornylidene)diphenol,4,4′-dihydroxybiphenol, o-, m- and p-dihydroxybenzene,4,4′-isopropylidenediphenol, 4,4′-isopropylidenebis(2,6-dichlorophenol),2,5-naphthalenediol, p-xylylenediol, cyclopentane-1,2-diol,cyclohexane-1,2-diol, cyclohexane-1,4-diol, and etherified diphenolssuch as bisphenol A-alkylene oxide adducts, and so forth. A small amountof a polyhydric alcohol having three or more hydroxyl groups may be usedin combination, as the case may be.

As the polyhydric alcohol having three or more hydroxyl groups, theremay be mentioned glycerol, trimethylolpropane, 1,2,6-hexanetriol,trimethylolethane, pentaerythritol, dipentaerythritol,tripentaerythritol and sorbitol, among others.

The polyol should preferably have a molecular weight of 600 to 6000,more preferably 1000 to 5000. Examples of polyester polyols includehydroxyl-terminated polyester polyol and polycaprolactone. The former isproduced by polymerizing an aliphatic carboxylic acid (such as malonicacid, succinic acid, and adipic acid) or an aromatic carboxylic acid(such as phthalic acid and terephthalic acid) or a mixture thereof withan aliphatic glycol (such as ethylene glycol, propylene glycol anddiethylene glycol) or a triol (such as trimethylolpropane and glycerin).The latter is obtained by the ring opening polymerization of lactone.

Suitable polyesters of the present invention, include but are notlimited to aromatic polyester polyols such as those made with phthallicanhydride (PA), dimethylterapthalate (DMT) polyethyleneterapthalate(PET) and aliphatic polyesters, and the like. Other suitablecommercially available polyesther polyol includes Inolex Lexorez®polyols, Bayer AG Desmophen® polyols, Stepan Stepanpol® polyols,Terathane® polyols.

The Polyurethane Prepolymer Isocyanate-Terminated PolyurethanePrepolymer

Isocyanate-terminated polyurethane prepolymers, useful in the presentinvention, are prepared by reacting an excess of organic polyisocyanatewith one or more of the foregoing hydroxy terminated polyester polyolsand/or copolymers, generally, in the presence of a catalyst. As usedherein, the term “polyisocyanate” means an organic compound possessingtwo or more isocyanate groups. The reaction temperature is typically inthe range of from about 60° to about 90° C.; the reaction time istypically from about 24 to about 48 hours.

In addition to the hydroxyl-terminated polyester-based polymer, thereaction mixture can contain one or more chain extenders and/or one ormore other polyols. Examples of suitable chain extenders are polyhydricalcohols such as ethylene glycol, propylene glycol, propane-1,3-diol,butane-1,4-diol, hexane-1,6-diol, diethylene glycol, triethylene glycol,tetraethylene glycol, dipropylene glycol, triethylene glycol,tetrathylene glycol, dipropylene glycol, tripropylene glycol,tetrapropylene glycol and the like. Additional polyols include polyetherpolyols, polyester polyols, polyetherester polyols, polyesteretherpolyols, polybutadienediols, polyoxyalkylene diols, polyoxyalkylenetriols, polytetramethylene glycols, polycaprolactone diols and triols,and the like, all of which possess at least two primary hydroxyl groups.

Suitable organic polyisocyanates include any of the known andconventional organic polyisocyanates, especially organic diisocyanates,from which polyurethane polymers have heretofore been prepared. Usefuldiisocyanates include, for example, 2,4-toluene diisocyanate,2,6-toluene diisocyanate, 4,4′ diphenyl-methanediisocyanate, isophoronediisocyanate, dicyclohexylmethane-4,4′-diisocyanate, various liquiddiphenylmethane-diisocyantes containing a mixture of 2,4- and 4,4′isomers, Desmodur N® (Bayer) and the like, and mixtures thereof.Isophorone diisocyanate is especially advantageous for use in preparingthe polyurethane prepolymers herein.

Suitable catalysts useful in the preparation of the polyurethaneprepolymers are known in the art, e.g., organoamine and organotincatalysts. Suitable catalysts include dialkyltin dicarboxylates such asdibutyltin dilaurate and dibutyltin acetate, tertiary amines, thestannous salts of carboxylic acids such as stannous octoate and stannousacetate, and the like.

To prepare isocyanate-terminated polyurethane prepolymers, at least aslight excess of the isocyanate equivalents (NCO groups) with respect tothe hydroxyl equivalents (OH groups) is employed to terminate thepolyester polyol and/or copolymer(s) with isocyanate groups.Advantageously, the molar ratio of NCO to OH is from about 1.1 to about4.0 depending on the selection of the particular hydroxyl-terminatedpolyester polyol and/or copolymer(s), optional chain extenders andoptional non-butadiene based polyols.

Hydroxyl-Terminated Polyurethane Prepolymer

Hydroxyl-terminated polyurethane prepolymers, useful in the presentinvention, can be prepared by the reaction of an organic polyisocyanate,e.g., a diisocyanate such as any of those mentioned above, andadvantageously isophorone diisocyanate, with a stoichiometric excess ofthe selected hydroxyl-terminated polyester polyol and/or copolymer(s).Depending on the reactivity of the respective reactants, a catalyst suchas any of those mentioned above can be employed. The reactiontemperature is typically in the range of from about 60° to about 90° C.;the reaction time is typically on the order of from about 24 to about 48hours. The reaction mixture can also contain one or more chain extendersand/or other polyols such as any of those mentioned above.

To prepare the hydroxyl group-terminated polyurethane prepolymers, atleast a slight excess of the hydroxyl equivalents (OH groups) withrespect to the NCO isocyanate equivalents (NCO groups) is employed toterminate the polyester chains with hydroxyl groups. Advantageously, themolar ratio of NCO to OH is from about 0.3 to about 0.95, and morepreferably from about 0.5 to about 0.90, depending on the specifichydroxyl-terminated polyester employed.

The Silylated Polyurethane Prepolymer Silylated Isocyanate-TerminatedPolyurethane Prepolymer

Silylation of the isocyanate-terminated polyurethane prepolymerdescribed herein above can be accomplished by reacting the prepolymerwith a silane possessing at least one hydrolyzable group and at leastone functionality which is reactive for isocyanate, i.e., an activehydrogen-containing group such as hydroxyl, carboxylic acid, mercapto,primary amino or secondary amino. Advantageously, the silane is aprimary or secondary aminosilane of the general formula:

wherein R¹ is hydrogen or an alkyl group of from 1 to 10 carbon atoms,R² is a divalent alkylene group of from 3 to 10 carbon atoms, R³ and R⁴each independently is an alkyl group of from 1 to 6 carbon atoms or anaryl group of from 6 to 8 carbon atoms, and x has a value of 0, 1 or 2.

Examples of aminosilanes for use in the silylation procedure herein are3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane,4-amino-3,3-dimethylbutyltrimethoxysilane,4-amino-3,3-dimethylbutyldimethoxymethylsilane,N-methyl-3-amino-2-methylpropyltrimethoxysilane,N-ethyl-3-amino-2-methylpropyltri-methoxysilane,N-ethyl-3-amino-2-methylpropyldiethoxymethylsilane,N-ethyl-3-amino-2-methylpropyltriethoxy silane,N-ethyl-3-amino-2-methylpropylmethyldimethoxysilane,N-butyl-3-amino-2-methylpropyltrimethoxysilane, 3(N-methyl-2-amino-1-methyl-1-ethoxy)-propyltrimethoxysilane,N-ethyl-4-amino-3,3-dimethylbutyldimethoxy-methylsilane andN-ethyl-4-amino-3,3-dimethylbutyltrimethoxysilane trimethoxysilane.

For applications such as use in sealant and coating compositions, thepolyurethane prepolymers can be substantially fully silylated, i.e.,all, or substantially all, of the isocyanate groups can be reacted withsilane to provide a completely silylated polyurethane polymer.

However, where the silylated polyurethane polymer is to be incorporatedinto pressure sensitive adhesive compositions, it is important that thesilylation be conducted to less than completion in order that the extentof crosslinking that occurs on subsequent cure of the silylated polymernot be so great as to adversely affect, and even eliminate, the pressuresensitive adhesive characteristics of the crosslinked polymer.

In conducting a partial silylation reaction, it can be useful to includea primary monoamine such as N-ethylbutylamine or similar cappingreactant together with the silane as the amine will readily end-capisocyanate groups thereby precluding them from reacting with the silane.The optimal amounts of silane and optional amine for achieving thisless-than-complete silylation operation can be readily determined for agiven isocyanate-terminated prepolymer employing known and conventionalexperimental techniques. Silylation of not more than about 95 percent,and advantageously not more than about 90 percent, of the totalisocyanate groups present in the prepolymer is generally suitable formost pressure sensitive adhesive applications.

Silylated Hydroxyl-Terminated Polyurethane Prepolymer

Silylation of the hydroxyl-terminated polyurethane prepolymer describedherein above can be accomplished by reacting the prepolymer with anisocyanatosilane. Suitable isocyanatosilanes are those of the generalformula:

wherein R¹ is a divalent alkylene group of from 3 to 10 carbon atoms, R²and R³ each independently is an alkyl group of from 1 to 6 carbon atomsor an aryl group of from 6 to 8 carbon atoms, and x has a value of 0, 1or 2.

Examples of such isocyanatosilanes for use in the silylation procedureare λ-isocyanatopropyltrimethoxysilane,λ-isocyanatopropyltriethoxy-silane,λ-isocyanatomethylpropyltrimethoxysilane,λ-isocyanatomethylpropyltriethoxysilane,λ-isocyanatopropylmethyldimethoxysilane,λ-isocyanatopropyldimethylmethoxysilane andλ-isocyanatomethylpropyldimethylmethoxysilane.

As in the case of the silylated isocyanate-terminated polyurethanesdescribed above, the silylation of the hydroxyl-terminated polyurethaneprepolymers herein will be substantially complete, i.e., essentially nohydroxyl groups will be present following silylation, where thesilylated polymers are to be incorporated in such products as sealantsand coatings. However, silylation will be incomplete, or partial, wherethe silylated polymers are to be incorporated in pressure sensitiveadhesive compositions. In the case of incomplete silylation, levels ofsilylation of not more than about 95 percent, and advantageously, notmore than about 90 percent, of the total hydroxyl groups present in theprepolymer is generally suitable and can be achieved by appropriateadjustment of the amounts of isocyanatosilane being reacted for a givenprepolymer.

In order to facilitate control over the extent of incomplete silylation,it may be advantageous to include a hydroxyl-reactive monofunctionalreactant with the isocyanatosilane. Suitable reactants for this purposeinclude monoisocyanates such as n-butylisocyanate. These and similarreactants serve to cap some of the hydroxyl groups of the prepolymerpreventing them from undergoing silylation. Amounts of suchhydroxyl-reactive monomeric reactants and isocyanatosilanes that can beutilized for partial silylation herein can be readily determined for aspecific hydroxyl-terminated polyurethane prepolymer employing routineexperimental testing.

In one embodiment of the invention, additional adhesive materials, suchas, for example, silane-terminated polybutadiene polyurethane orsilicone or organic (natural rubber, SBR, SIS, acrylic, isoprene,polyurethanes) adhesives can be blended with silane-terminated polyesterpolyurethane to prepare adhesives that offer a means of modifying thepeel adhesion, as shown in the Examples described below, and otherproperties, e.g., drug delivery rates. In the later case, typicallyadhesives, such as, for example PIB (polyisobutylene), acrylic andsilicone are blended for adhesion against skin and modification of drugdelivery rates.

Pressure Sensitive Adhesive Compositions

Pressure sensitive adhesive compositions possessing superior adhesiveand cohesive properties can be obtained with the partially silylatedpolyurethanes described above. In addition to the partially silylatedpolyurethanes, a pressure sensitive adhesive composition in accordancewith the invention will typically include one or more additives such asfillers, tackifiers, silane adhesion promoters, plasticizers, solvents,thixotropic agents, U.V. stabilizers, antioxidants, cure catalysts,etc., in the usual amounts.

Typical fillers suitable for addition to the pressure-sensitive adhesivecompositions of this invention include fumed silica, precipitated silicaand calcium carbonates. Treated calcium carbonates having particle sizesfrom about 0.07μ to about 4μ are particularly useful and are availableunder several trade names: Ultra Pflex, Super Pflex, Hi Pflex fromSpecialty in Minerals; Winnofil SPM, SPT from Zeneca Resins; Hubercarblat, Hubercarb 3Qt and Hubercarb W from Huber and Kotomite from ECC.These fillers can be used either alone or in combination. The fillerscan comprise up to about 200 parts per 100 parts of the silylatedpolymer component(s) with from about 80 to about 150 parts filler per100 parts polymer being suitable for many adhesive applications.

The pressure sensitive adhesive composition can contain from about 20 toabout 60 parts, and advantageously from about 30 to about 50 parts, ofone or more known of conventional tackifiers per 100 parts of silylatedpolyurethane polymer. Examples of suitable tackifiers are MQ siliconeresins (for which a curing catalyst such as benzoyl peroxide willordinarily be included), terpene oligomers, coumarone/indene resins,aliphatic, petrochemical resins, and modified phenolic resins.

Silane adhesion promoters can be employed at levels of from about 0.5 toabout 5 parts per hundred parts of the silylated polyurethane polymerwith from about 0.8 to about 1.5 parts per hundred parts polymer beingespecially advantageous. Suitable adhesion promoters include Silquest®A-1120 silane, Silquest® A-2120 silane, Silquest® A-1170 silane andSilquest® A-187 silane, all of which are available from GE Silicones.

Exemplary plasticizers include phthalates, dipropylene and diethyleneglycol dibenzoates and mixtures thereof, epoxidized soybean oil, and thelike. Dioctyl and diisodecylphthalate are commercially available underthe trade names Jayflex® DOP and JayFlex® DIDP from Exxon Chemical. Thedibenzoates are available as Benzoflex® 9-88, Benzoflex® 50 andBenzoflex® 400 from Velsicol Chemical Corporation. Epoxidized soybeanoil is available from Houghton Chemical Corporation as Flexol® EPO. Theplasticizer can comprise up to about 100 parts of the silylatedpolyurethane polymer with from about 40 to about 80 parts per hundredparts of silylated polymer being satisfactory in many cases.

Useful solvents include aromatic, aliphatic and esters ranging inamounts of from about 25 to about 75 per hundred parts by weight ofsilylated polyurethane prepolymer.

Illustrative of useful thixotropic agents are various castor waxes,fumed silica, treated clays and polyamides. These additives typicallycomprise about 1 to about 10 parts per hundred parts of silylatedpolyurethane prepolymer with from about 1 to about 6 parts being usefulfor most applications. The thixotropes include those available as:Aerosil® from Degussa, Cabo-Sil® TS 720 from Cabot, Castorwax® fromCasChem, Thixatrol® and Thixcin® from Rheox and Dislon® from KingIndustries. If the thixotrope is reactive with silane (e.g., silica),adjustments to the amount formulated may be needed to compensatetherefor.

U. V. stabilizers and/or antioxidants can be incorporated into thepressure sensitive adhesive compositions of this invention in an amountof from 0 to about 5 parts per hundred parts silylated polyurethanepolymer with from about 0.5 to about 2 parts providing generally goodresults. These materials are available from Ciba-Geigy under the tradenames Tinuvin® 770, Tinuvin® 327, Tinuvin® 213, Tinuvin® 622 andIrganox® 1010.

Suitable cure catalysts are the same as those previously described forpreparation of the silylated polyurethane polymers. The catalyststypically compromise from about 0.01 to about 3 parts per hundred partspolymer with from about 0.01 to about 1.0 parts per hundred parts ofpolymer being entirely suitable in many cases.

After mixing, the pressure sensitive adhesive compositions are cured byexposure to moisture. Curing conditions typically include ambienttemperature, e.g., about 23° C. and 50% relative humidity for 3 days and37° C. and 95% relative humidity for another 4 days. Alternatively watercan be dissolved in an appropriate solvent such as isopropanol followedby mixing with the adhesive composition and coated, cured inconventional adhesive cure ovens known in the art.

The following examples are illustrative of the silylated polyurethanepolymers and blends of silylated polyurethane polymers of this inventionand pressure sensitive adhesive compositions containing same.

Example 1

To a resin reaction vessel equipped with mixing capability, condenser,nitrogen atmosphere and heating was added 11.0 g of hydroxyl terminatedpolyester Lexorez® 1842-90 a poly(diethylene glycol glycerine adipate)resin containing a hydroxyl number of 90, 99.0 g of hydroxyl terminatedpolyester Lexorez® 1640-35 a poly(1,4-butanediol neopentyl glycoladipate) resin containing a hydroxyl number of 35, and 174.0 g ethylacetate. The average OH groups calculated for this blend of polyols was2.22. These resins were refluxed to reduce moisture. It was cooled to75-80° C. then 0.09 g of a 10 wt % solution of dibutyltinbis(acetylacetonate) was added and agitated for 15 minutes. Next 8.3 gof isophorone diisocyanate (NCO/OH=0.93) was added with agitation. Thetemperature was maintained at 75+/−1° C. until the wt % NCO wasdetermined per standard methodology was found to be less than 0.01 wt %.At this point 1.0 g of 3-isocyanatopropyltrimethoxysilane was added andagitation continued at temperature until wt % NCO was determined to be0.01%. Solids were determined to be 39.2 wt % and viscosity of 4800 cpsusing a Brookfield HATDV-II, spindle 6 at 50 rpm.

Approximately a 25 g sample of the reaction product was dissolved in 13g of ethyl acetate, 2 drops of a 10 wt % dimethyltinbis[(1-oxoneodecyl)oxy]stannane in toluene solution, 0.4 g water weremixed thoroughly then allowed to set for 30 minutes at which time thesolution was bar coated onto 50 micron PET film. After a 10 minute airdry period the adhesive was placed in a 150° C. oven for 2 minutes.Adhesive thickness was determined to be 22 microns. Lap shear sampleswere prepared with 1.0 inch×1.0 inch overlap onto a glass slide and 10 gweight attached then placed in stirred xylene using a jig to achieve a2° off-set from vertical. Time to failure was >24 hours. A similar lapshear failure time of 6 hours 30 minutes was determined using a textureddelrin cassette with 0.25 inch×0.87 inch lap, 10 g weight attached for57 micron adhesive thickness coated tapes. The Shear Adhesion FailureTemperature (SAFT) for a 1 inch×1 inch on stainless steel, 1 Kg weightwas determined to be 220° C. for the 22 micron adhesive thickness coatedtapes. Probe tack results also for the 22 micron adhesive thicknesstapes for 100 g/cm² applied force was 653 g/cm², and at 1000 g/cm²applied force was 752 g/cm². Peel Adhesion for 1 inch tapes applied toand allowed 20 minute dwell prior to testing, then peeled at 300mm/minute 180° was 1494 g/25 mm, glass 1040 g/25 mm, aluminum 1529 g/25mm, smooth delrin 468 g/25 mm, BOPP 1160 g/25 mm, polycarbonate 1703g/25 mm, PMMA 2360 g/25 mm, PVC 1118 g/25 mm, and HDPE 823 g/25 mmdemonstrating a wide range of peel adhesions.

Example 2

Example 2 (Illustrates blending with two silylated polyurethaneadhesives of different compositions-polybutadiene and polyester).

Adhesive I of Example 2 was prepared as follows: To a resin reactionvessel equipped with mixing capability, condenser, nitrogen atmosphereand heating was added 72.5 g of hydroxyl terminated polybutadieneKrasol® LBH-P 2000 resin containing a hydroxyl number of 46, 145.0 g ofhydroxyl terminated polybutadiene Krasol® LBH-P 5000 resin containing ahydroxyl number of 21.7, 32.5 g of hydroxyl terminated polybutadienePoly bd R20LM resin containing a hydroxyl number of 101 and 400.3 g ofethyl acetate. The average OH groups calculated for this polyol was 2.1.Refluxed for 2 hours to dry the mixture followed by cooling to 75-80° C.To this was added 0.27 g of a 10 wt % toluene solution ofdimethylbis[(1-oxoneodecyl)oxy]stannane with agitation for 15 minutes.Next 18.6 g of isophorone diisocyanate was added for an NCO/OHequivalent ratio of 0.95. The reactants were heated at 75-80° C. untilthe wt % NCO was determined per standard methodology and found to be 0.0wt % followed by drop wise addition of 1.34 gisocyanatopropyltrimethoxysilane. Heating was continued until wt % NCOwas 0.0 wt % then cool to room temperature.

Adhesive II of Example 2 consisted of a silylated polyester polyurethaneand was prepared as follows: To a resin reaction vessel equipped withmixing capability, condenser, nitrogen atmosphere and heating was added14.0 g of hydroxyl terminated poly(diethylene glycol glycerine adipate)resin containing a hydroxyl number of 90 with approximately 4.2 OHgroups, 126.0 g poly(1,4-butanediol neopentyl glycol adipate) diol resincontaining a hydroxyl number of 35, and 221.4 g of ethyl acetate. Theaverage OH groups calculated for this blend of polyols was 2.22.Refluxed for 2 hours to dry the mixture followed by cooling toapproximately 75° C. To this was added 0.09 g of a 10 wt % toluenesolution of dimethylbis[(1-oxoneodecyl)oxy]stannane with agitation for15 minutes. Next 10.6 g of isophorone diisocyanate was added for anNCO/OH equivalent ratio of 0.93. The reactants were heated atapproximately 75° C. until the wt % NCO was determined per standardmethodology and found to be 0.00 wt % then 1.3 gisocyanatopropyltrimethoxysilane was added and heated until 0.00 wt %NCO determined.

Adhesives I and II of Example 2 were blended 50/50 w/w then bar coated(Adhesives I and II were similarly bar coated) to give a 40 micronadhesive thickness on 50 micron PET film, air dried 10 minutes thencured 2 minutes at 150° C. These were then tested after one week at roomtemperature. Peel adhesion per PSTC-101 using standard stainless steeltest panels was recorder and is presented in Table 1.

TABLE 1 Ratio of I/II Adhesive Peel Adhesion, Blends g/25 mm 100/0  89550/50 1257  0/100 1349

Example 3

Example 3 (Illustrates Example 1 with an average 2.11 OH groups for thisblend of polyols).

Example 3 was prepared as follows: To a resin reaction vessel equippedwith mixing capability, condenser, nitrogen atmosphere and heating wasadded 7.0 g of hydroxyl terminated polyester Lexorez® 1842-90 apoly(diethylene glycol glycerine adipate) resin containing a hydroxylnumber of 90, 133.0 g of hydroxyl terminated polyester Lexorez® 1640-35a poly(1,4-butanediol neopentyl glycol adipate) resin containing ahydroxyl number of 35, and 220.4 g ethyl acetate. The average OH groupscalculated for this blend of polyols was 2.11. These resins wererefluxed to reduce moisture. It was cooled to 75-80° C. then 0.18 g of a10 wt % solution of dibutyltin bis(acetylacetonate) was added andagitated for 15 minutes. Next 9.9 g of isophorone diisocyanate(NCO/OH=0.93) was added with agitation. The temperature was maintainedat 75+/−1° C. until the wt % NCO was determined per standard methodologywas found to be 0.01 wt %. At this point 1.28 g of3-isocyanatopropyltrimethoxysilane was added and agitation continued attemperature until wt % NCO was determined to be 0.004%. Solids adjustedto 40 wt % and viscosity of 416 cps determined using a BrookfieldHATDV-II, spindle 4 at 50 rpm. Approximately a 25 g sample of thereaction product was dissolved in 13 g of ethyl acetate, 2 drops of a 10wt % dimethyltin bis[(1-oxoneodecyl)oxy]stannane in toluene solution,0.2 g water were mixed thoroughly then allowed to set for 30 minutes atwhich time the solution was bar coated onto 50 micron PET film. After a10 minute air dry period the adhesive was placed in a 135° C. oven for 3minutes. Adhesive thickness was determined to be 25 microns. Peeladhesion (PSTC-101) for 1 inch tapes applied to and allowed 20 minutedwell prior to testing failed cohesively.

Example 4

Example 4 (Illustrates Example 1 with an average 2.06 OH groups for thisblend of polyols).

Example 4 was prepared as follows: To a resin reaction vessel equippedwith mixing capability, condenser, nitrogen atmosphere and heating wasadded 3.5 g of hydroxyl terminated polyester Lexorez® 1842-90 apoly(diethylene glycol glycerine adipate) resin containing a hydroxylnumber of 90, 133.0 g of hydroxyl terminated polyester Lexorez® 1640-35a poly(1,4-butanediol neopentyl glycol adipate) resin containing ahydroxyl number of 35, and 220.4 g ethyl acetate. The average OH groupscalculated for this blend of polyols was 2.06. These resins wererefluxed to reduce moisture. It was cooled to 75-80° C. then 0.18 g of a10 wt % solution of dibutyltin bis(acetylacetonate) was added andagitated for 15 minutes. Next 9.9 g of isophorone diisocyanate(NCO/OH=0.93) was added with agitation. The temperature was maintainedat 75+/−1° C. until the wt % NCO was determined per standard methodologywas found to be 0.01 wt %. At this point 1.28 g of3-isocyanatopropyltrimethoxysilane was added and agitation continued attemperature until wt % NCO was determined to be 0.004%. Solids adjustedto 40 wt % and viscosity of 416 cps determined using a BrookfieldHATDV-II, spindle 4 at 50 rpm. Approximately a 25 g sample of thereaction product was dissolved in 13 g of ethyl acetate, 2 drops of a 10wt % dimethyltin bis[(1-oxoneodecyl)oxy]stannane in toluene solution,0.2 g water were mixed thoroughly then allowed to set for 30 minutes atwhich time the solution was bar coated onto 50 micron PET film. After a10 minute air dry period the adhesive was placed in a 135° C. oven for 3minutes. Adhesive thickness was determined to be 25 microns. Peeladhesion (PSTC-101) for 1 inch tapes applied to and allowed 20 minutedwell prior to testing failed cohesively.

Example 5

Example 4 (illustrates selection of catalyst can provide an adhesivebetter than found in Example 4) was repeated except the dibutyltinbis(acetylacetonate) catalyst was replaced by dimethyltinbis[(1-oxoneodecyl)oxy]stannane. Reaction product viscosity was 1350 cpsat 38.1 wt % solids. Approximately a 25 g sample of the reaction productwas dissolved in 13 g of ethyl acetate, 2 drops of a 10 wt % dimethyltinbis[(1-oxoneodecyl)oxy]stannane in toluene solution, 0.2 g water weremixed thoroughly then allowed to set for 30 minutes at which time thesolution was bar coated onto 50 micron PET film. After a 10 minute airdry period the adhesive was placed in a 80° C. oven for 3 minutes.Adhesive thickness was determined to be 50 microns. Peel adhesion(PSTC-101) for 1 inch tapes applied to stainless steel was 2202 g/in,glass 2572 g/in and aluminum 2264 g/in, all adhesively failed. A 6.3mm×25 mm lap shear applied to a textured Delran cassette with a 10 gweight attached, tested in duplicate were immersed in stirred xylene andthe time to failure determined to be 8 hours for the average. Adhesiveswell due to 24 hours immersion in xylene was also determined to be fourtimes initial adhesive thickness and appeared to be a swollen adhesiveand did not dissolve.

Example 6

Example 6 (illustrates blending Example 5 adhesive with other adhesives)

On a solids basis adhesives were blended. Example 5 adhesive wasformulated prior to blending with other adhesives as per Example 5.Tapes were aged one week at room temperature then tested per PSATC-101.Peel adhesion results for the various blends of example 6 are displayedin Table 1A.

TABLE 1A Example 5% PSTC-101 Peel Adhesive Other Adhesive Adhesion 20Ashland 1085-38¹ 1884 g/25 mm 40 Ashland 1085-38¹ 1892 g/25 mm 20Silgrip PSA6574² 2107 g/25 mm ¹Ashland Chemical ²GE AdvancedMaterials-Silicones

Example 7

Example 7 (Illustrates Example 1 with polyester diol based silylatedpolyurethane polymer).

Example 7 was prepared as follows: To a resin reaction vessel equippedwith mixing capability, condenser, nitrogen atmosphere and heating wasadded 140.0 g of hydroxyl terminated polyester Lexorez® 1640-35 apoly(1,4-butanediol neopentyl glycol adipate) resin containing ahydroxyl number of 35, and 219.3 g ethyl acetate. The average OH groupscalculated for this blend of polyols was 2.00. These resins wererefluxed to reduce moisture. It was cooled to 75-80° C. then 0.18 g of a10 wt % solution of dibutyltin bis(acetylacetonate) was added andagitated for 15 minutes. Next 9.1 g of isophorone diisocyanate(NCO/OH=0.93) was added with agitation. The temperature was maintainedat 75+/−1° C. until the wt % NCO was determined per standard methodologywas found to be 0.00 wt %. At this point 1.25 g of3-isocyanatopropyltrimethoxysilane was added and agitation continued attemperature until wt % NCO was determined to be 0.004%. Solids adjustedto 40 wt % and viscosity of 248 cps determined using a BrookfieldHATDV-II, spindle 4 at 50 rpm. Approximately a 25 g sample of thereaction product was dissolved in 13 g of ethyl acetate, 2 drops of a110 wt % dimethyltin bis[(1-oxoneodecyl)oxy]stannane in toluenesolution, 0.2 g water were mixed thoroughly then allowed to set for 30minutes at which time the solution was bar coated onto 50 micron PETfilm. After a 10 minute air dry period the adhesive was placed in a 135°C. oven for 3 minutes. Adhesive thickness was determined to be 25microns. Peel adhesion (PSTC-101) for 1 inch tapes applied to andallowed 20 minute dwell prior to testing failed cohesively.

Example 8

Example 8 (illustrates further that even with alternate catalyst,average OH groups calculated polyols was 2.00, failed cohesively) wasrepeated except the dibutyltin bis(acetylacetonate) catalyst wasreplaced by dimethyltin bis[(1-oxoneodecyl)oxy]stannane. Reactionproduct viscosity was 3700 cps at 65.0 wt % solids. Approximately a 25 gsample of the reaction product was dissolved in 29 g of ethyl acetate, 2drops of a 10 wt % dimethyltin bis[(1-oxoneodecyl)oxy]stannane intoluene solution, 0.3 g water were mixed thoroughly then allowed to setfor 30 minutes at which time the solution was bar coated onto 50 micronPET film. After a 10 minute air dry period the adhesive was placed in a80° C. oven for 3 minutes. Adhesive thickness was determined to be 50microns. Peel adhesion (PSTC-101) for 1 inch tapes applied to stainlesssteel cohesively failed.

Example 9

Example 9 (Illustrates Example 1 with an average 2.22 OH groups for thisblend of polyols and the use of aminosilane capping agent).

Example 9 was prepared as follows: To a resin reaction vessel equippedwith mixing capability, condenser, nitrogen atmosphere and heating wasadded 14.0 g of hydroxyl terminated polyester Lexorez® 1842-90 apoly(diethylene glycol glycerine adipate) resin containing a hydroxylnumber of 90, 126.0 g of hydroxyl terminated polyester Lexorez® 1640-35a poly(1,4-butanediol neopentyl glycol adipate) resin containing ahydroxyl number of 35, and 225.0 g ethyl acetate. The average OH groupscalculated for this blend of polyols was 2.22. These resins wererefluxed to reduce moisture. It was cooled to 75-80° C. then 0.08 g of a10 wt % solution of dibutyltin bis(acetylacetonate) was added andagitated for 15 minutes. Next 10.8 g of isophorone diisocyanate(NCO/OH=1.07) was added with agitation. The temperature was maintainedat 75+/−1° C. until the wt % NCO was determined per standard methodologywas found to be 0.069 wt %. At this point 1.31 g ofN-ethyl-aminoisobutyltrimethoxysilane was added and agitation continuedwhile cooling to room temperature. Solids adjusted to 41 wt % andviscosity of 336 cps determined using a Brookfield HATDV-II, spindle 4at 50 rpm. Approximately a 25 g sample of the reaction product wasdissolved in 13 g of ethyl acetate, 2 drops of a 10 wt % dimethyltinbis[(1-oxoneodecyl)oxy]stannane in toluene solution, 0.2 g water weremixed thoroughly then allowed to set for 30 minutes at which time thesolution was bar coated onto 50 micron PET film. After a 10 minute airdry period the adhesive was placed in a 150° C. oven for 3 minutes.Adhesive thickness was determined to be 25 microns. Peel Adhesion(PSTC-101) for 1 inch tapes applied to and allowed 20 minute dwell priorto testing, then peeled at 300 mm/minute 180° was 1494 g/25 mm onstainless steel, glass gave 2140 g/25 mm, aluminum 2218 g/25 mm, PVC2044 g/25 mm, and HDPE 2210 g/25 mm. A 6.3 mm×25 mm lap shear applied toa textured Delran cassette with a 10 g weight attached, tested intriplicate were immersed in stirred xylene and the time to failuredetermined to be 6.7 hours for the average. Adhesive swell due to 24hours immersion in xylene was also determined to be five times initialadhesive thickness and appeared to be a swollen adhesive and did notdissolve.

Example 10

Example 10 (Illustrates Example 1 with an average 2.22 OH groups forthis blend of polyols and a crystalline diol melting range 35-45 C).

Example 10 was prepared as follows: To a resin reaction vessel equippedwith mixing capability, condenser, nitrogen atmosphere and heating wasadded 10.0 g of hydroxyl terminated polyester Lexorez® 1842-90 apoly(diethylene glycol glycerine adipate) resin containing a hydroxylnumber of 90, 90.0 g of hydroxyl terminated polyester Desmophen®S-1015-35 a polyester diol resin containing a hydroxyl number of 35 anda melt transition temperature range of 35-45° C., and 239.0 g ethylacetate. The average OH groups calculated for this blend of polyols was2.26. These resins were refluxed to reduce moisture. It was cooled to75-80° C. then 0.09 g of a 10 wt % solution of dibutyltinbis(acetylacetonate) was added and agitated for 15 minutes. Next 7.6 gof isophorone diisocyanate (NCO/OH=0.93) was added with agitation. Thetemperature was maintained at 75+/−1° C. until the wt % NCO wasdetermined per standard methodology was found to be 0.047 wt %. At thispoint 0.88 g of 3-isocyanatopropyltrimethoxysilane was added andagitation continued at temperature until wt % NCO was determined to be0.003%. then agitation continued while cooling to room temperature.Solids adjusted to 31 wt % and viscosity of 12200 cps determined using aBrookfield HATDV-II, spindle 3 at 50 rpm. Approximately a 25 g sample ofthe reaction product was dissolved in 13 g of ethyl acetate, 2 drops ofa 10 wt % dimethyltin bis[(1-oxoneodecyl)oxy]stannane in toluenesolution, 0.2 g water were mixed thoroughly then allowed to set for 30minutes at which time the solution was bar coated onto 50 micron PETfilm. After a 10 minute air dry period the adhesive was placed in a 135°C. oven for 3 minutes. Adhesive thickness was determined to be 25microns. Peel Adhesion (PSTC-101) for 1 inch tapes applied to andallowed 20 minute dwell prior to testing, then peeled at 300 mm/minute180° was 1394 g/25 mm on stainless steel, glass gave 1638 g/25 mm,aluminum 1389 g/25 mm, PVC 1346 g/25 mm, and HDPE 1268 g/25 mm.

Example 11

Example 11 (Illustrates Example 1 with an average 2.22 OH groups forthis blend of polyols and a crystalline polyester diol with higher melttransition temperature range 75-80 C at which a hot melt adhesive ratherthan pressure sensitive adhesive was obtained).

Example 11 was prepared as follows: To a resin reaction vessel equippedwith mixing capability, condenser, nitrogen atmosphere and heating wasadded 10.0 g of hydroxyl terminated polyester Lexorez® 1842-90 apoly(diethylene glycol glycerine adipate) resin containing a hydroxylnumber of 90, 90.0 g of hydroxyl terminated polyester Desmophen®S-1072-30 a polyester diol resin containing a hydroxyl number of 35 anda melt transition temperature range of 75-80° C., and 237.3 g ethylacetate. The average OH groups calculated for this blend of polyols was2.22. These resins were refluxed to reduce moisture. It was cooled to75-80° C. then 0.09 g of a 10 wt % solution of dibutyltinbis(acetylacetonate) was added and agitated for 15 minutes. Next 7.6 gof isophorone diisocyanate (NCO/OH=0.93) was added with agitation. Thetemperature was maintained at 75+/−1° C. until the wt % NCO wasdetermined per standard methodology was found to be 0.08 wt %. At thispoint 0.87 g of 3-isocyanatopropyltrimethoxysilane was added andagitation continued at temperature until wt % NCO was determined to be0.01%. Agitation continued while cooling to room temperature. Solidswere determined to be 30 wt % and the composition was a hot meltadhesive rather than being a pressure sensitive adhesive at roomtemperature.

Example 12

Example 12 (Illustrates Example 1 possessing an average 2.22 OH groupsfor this blend of polyols and a crystalline polyester diol with highermelt transition temperature range 50-60 C at which a hot melt adhesiverather than pressure sensitive adhesive was obtained).

Example 12 was prepared as follows: To a resin reaction vessel equippedwith mixing capability, condenser, nitrogen atmosphere and heating wasadded 10.0 g of hydroxyl terminated polyester Lexorez® 1842-90 apoly(diethylene glycol glycerine adipate) resin containing a hydroxylnumber of 90, 90.0 g of hydroxyl terminated polyester Desmophen® 2505 apolyester diol resin containing a hydroxyl number of 28 and a melttransition temperature range of 50-60° C., and 236.4 g ethyl acetate.The average OH groups calculated for this blend of polyols was 2.22.These resins were refluxed to reduce moisture. It was cooled to 75-80°C. then 0.09 g of a 10 wt % solution of dibutyltin bis(acetylacetonate)was added and agitated for 15 minutes. 6.4 g of isophorone diisocyanate(NCO/OH=0.93) was added with agitation. The temperature was maintainedat 75+/−1° C. until the wt % NCO was determined per standard methodologywas found to be <0.01 wt %. 0.77 g of 3-isocyanatopropyltrimethoxysilanewas added and agitation continued at temperature until wt % NCO wasdetermined to be <0.01%. Agitation continued while cooling to roomtemperature. Solids were determined to be 32.5 wt %, viscosity 1240 cps.Approximately a 25 g sample of the reaction product was dissolved in 13g of ethyl acetate, 2 drops of a 10 wt % dimethyltinbis[(1-oxoneodecyl)oxy]stannane in toluene solution, 0.2 g water weremixed thoroughly then allowed to set for 30 minutes at which time thesolution was bar coated onto 50 micron PET film. After a 10 minute airdry period the adhesive was placed in a 75° C. oven for 30 minutes. Theadhesive coating was a hot melt adhesive rather than a pressuresensitive adhesive at room temperature.

While the process of the invention has been described with reference tocertain embodiments, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out the process of the invention but that theinvention will include all embodiments falling within the scope of theappended claims.

1. A silylated polyurethane composition comprising silylatedpolyurethane prepolymer prepared from a process which comprises: (a)reacting a polyol being a blend of two or more polyester polyolspossessing an average of hydroxyl group of the blend ranging from about2.05 to about 2.75 with a polyisocyanate in the presence of a catalystat a molar ratio of NCO to OH from about 0.3 to about 0.95 to provide ahydroxyl-terminated polyurethane prepolymer, (b) reacting saidhydroxyl-terminated polyurethane prepolymer with an isocyanatosilane toform said silylated polyurethane prepolymer, wherein less than 95percent of the hydroxyl-terminated polyurethane prepolymer is silylated,with the proviso that if said polyester polyol comprises a crystallinepolyester diol, said diol has a melting point of less than 50° C.
 2. Thesilylated polyurethane composition of claim 1 wherein said catalyst isselected from the group consisting of organoamine and organotin.
 3. Thesilylated polyurethane composition of claim 2 wherein said catalyst isselected from the group consisting of dialkyltin dicarboxylates,tertiary amines, stannous salts of carboxylic acids.
 4. The silylatedpolyurethane composition of claim 1 further comprising an additionaladhesive material.
 5. The silylated polyurethane composition of claim 4wherein the additional adhesive material is at least one selected fromthe group consisting of silane-terminated polyurethane, polyurethane,silicone, natural rubber, styrene butadiene rubber, styrene isoprenestyrene, isoprene, acrylic, and polyisobutylene.
 6. The silylatedpolyurethane composition of claim 1 wherein the isocyanatosilanes arethose of the general formula:

wherein R¹ is a divalent alkylene group of from 3 to 10 carbon atoms, R²and R³ each independently is an alkyl group of from 1 to 6 carbon atomsor an aryl group of from 6 to 8 carbon atoms, and x has a value of 0, 1or
 2. 7. The silylated polyurethane composition of claim 1 wherein theisocyanatosilanes is selected from the group consisting ofλ-isocyanatopropyltrimethoxysilane, λ-isocyanatopropyltriethoxy-silane,λ-isocyanatomethylpropyltrimethoxysilane,λ-isocyanatomethylpropyltriethoxysilane,λ-isocyanatopropylmethyldimethoxysilane,λ-isocyanatopropyldimethylmethoxysilane andλ-isocyanatomethylpropyldimethylmethoxysilane and mixtures thereof.
 8. Acurable pressure sensitive adhesive composition comprising a pressuresensitive adhesive amount of the silylated polyurethane composition ofclaim
 1. 9. A curable pressure sensitive adhesive composition comprisinga pressure sensitive adhesive amount of the silylated polyurethanecomposition of claim
 5. 10. The curable pressure sensitive adhesivecomposition of claim 8 comprising at least one additional componentselected from the group consisting of filler, tackifier, silane adhesionpromoter, plasticizer, solvent, thixotropic agent, U.V. stabilizer,antioxidant and curing catalyst.
 11. The curable pressure sensitiveadhesive composition of claim 10 wherein the tackifier is MQ tackifierresin containing curing catalyst therefor.
 12. The cured pressuresensitive adhesive composition of claim
 8. 13. The cured pressuresensitive adhesive composition of claim
 9. 14. The cured pressuresensitive adhesive composition of claim
 10. 15. The cured pressuresensitive adhesive composition of claim
 11. 16. The curable pressuresensitive adhesive composition of claim 9 comprising at least oneadditional component selected from the group consisting of filler,tackifier, silane adhesion promoter, plasticizer, solvent, thixotropicagent, U.V. stabilizer, antioxidant and curing catalyst.
 17. The curablepressure sensitive adhesive composition of claim 16 wherein thetackifier is MQ tackifier resin containing curing catalyst therefor. 18.The cured pressure sensitive adhesive composition of claim
 16. 19. Thecured pressure sensitive adhesive composition of claim
 17. 20. Thecomposition of claim 1 wherein said catalyst isdimethyltinbis[(1-oxoneodecyl)oxyl]stannane.
 21. The composition ofclaim 1 wherein the weight percent of Si in the silylated polyurethaneprepolymer is from 0.098% to 0.118%.
 22. The silylated polyurethanecomposition of claim 1 wherein said polyester polyol comprises acrystalline polyester polyol having a melting point of less than 50° C.23. The silylated polyurethane composition of claim 1 wherein saidpolyester polyol does not contain a crystalline polyester polyol havinga melting point of greater than 50° C.